A diagnosis of cancer in older persons is likely to be made in the context of comorbidity, or preexisting health conditions, unrelated to the cancer at the time of diagnosis. In some patients, comorbidity may be so severe as to impact directly on survival or prohibit the use of preferred anti-neoplastic therapies. At present, no established, valid way to incorporate comorbidity assessment into the care of older cancer patients exists. The Broad Long-Term Objective of this project is to improve the scientific understanding of the interaction between human aging, cancer, and comorbid health ailments. There are three Specific Aims: 1. To compare and contrast the prevalence of comorbid ailments and combinations of ailments across the adult age spectrum. 2. To develop and validate a prognostic model that incorporates cogent comorbid ailments for elderly cancer patients. 3. To compare the performance of the newly developed prognostic model with comparable existing benchmark prognostic models. This will be a prospective observational prognostic study. The population will consist of 28,615 adults with newly diagnosed cancers treated at one of 8 different hospitals in the United States; 15,109 (53%) will be 65 years and older. These hospitals collect patient and tumor information according to the Uniform Data Standards of the three main national cancer registry programs -- Commission on Cancer National Cancer Data Base, Surveillance, Epidemiology and End Results, and the Centers for. Disease Control National Program of Cancer Registries. These hospitals were selected as a. result of their previous participation in an NCI-sponsored comorbidity education program (R25CA68304). In that program registrars received formal training in comorbidity coding. The prognostic endpoint will be overall survival and we will model time until death. The minimum duration of follow up will be two years; 71% of the patients will have at least 3 years of follow-up. The anticipated numbers of events (i.e., deaths) will 8,012; 7,014, (88%) among patients >= 65. The research described in this application is unique because it combines comorbid health information collected in a valid and uniform way with standard cancer registry data elements. Better understanding of the type, severity, and prognostic impact of comorbid health conditions for elderly cancer patients will have a significant impact on tumor registry studies, observational studies comparing alternative treatments, assessment of disparities in health care, outcomes and health services research, and quality of care initiatives. The prognostic research proposed in this application is a fundamental first step in the incremental incorporation of comorbidity assessment into the care of the older patient with cancer and the assessment of the efficacy and safety of therapy.